Scotland reported six Omicron cases on Monday, some not linked to travel in southern Africa, raising concerns that the mutation-heavy coronavirus variant is already spreading in the community.

Britain as a whole has reported nine cases of the new variant, which the World Health Organization said on Monday was likely to spread internationally and posed a very high risk of infection surges. 

The four nations of the United Kingdom have all restricted travel to southern Africa, where the variant was first detected last week, in a bid to slow its spread.

But Scottish First Minister Nicola Sturgeon said not all of the six cases had recent travel history or known links with others who had travelled to southern Africa.

"This suggests that there might already be some community transmission of this variant," she told a news conference.

"There is no evidence yet that this is sustained, nor any evidence from the enhanced surveillance that it is widespread at this stage."

Sturgeon said the timeframe of the cases suggested it was unlikely but not impossible that there was a link to the COP26 climate change conference that took place in Glasgow earlier this month.